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通过差示扫描量热法(differential scanning calorimetry,DSC)研究了乙烯原位聚合线性低密度聚乙烯(LLDPE)在连续自成核退火过程中的分步结晶,得到产物链结构的支化非均匀性的信息.研究发现LLDPE在经过热分级处理后其熔融曲线呈多峰状,表明产物具有一定的非均匀性,不同长度链段所形成的晶片厚度在4～10nm之间;X射线衍射(XRD)结果表明,各不同晶面所对应的微晶尺寸在几十纳米左右.比较了其与乙烯和长链α-烯烃共聚物的DSC热分级曲线和XRD曲线,结果表明两者存在一定的统一性.由此认为可以利用乙烯与不同链长α-烯烃共聚的方法模拟乙烯原位聚合产物,从而简化了研究乙烯原位聚合产物结构的复杂性.
The fractional crystallization of LLDPE in continuous self-nucleation annealing was studied by differential scanning calorimetry (DSC). The branched non-uniform The results show that the melting curve of LLDPE is multimodal after thermal classification, indicating that the product has a certain degree of heterogeneity. The thickness of the films formed by different lengths of segments is between 4 and 10 nm. The X-ray diffraction XRD results show that the size of crystallites corresponding to different crystal planes is about several tens of nanometers.The DSC thermal grading curves and XRD curves of copolymers with ethylene and long chain α-olefins are compared, and the results show that there is a certain Therefore, it is considered that the method of ethylene copolymerization with different chain length alpha-olefins can be used to simulate the ethylene polymerization in situ, thereby simplifying the study of the complexity of the ethylene in situ polymerization product structure.